What You're Actually Replacing
When you "change" a garbage disposal, you are removing the entire unit from under your sink and installing a new one in its place. This is not a repair—it is a full swap. The disposal itself is a sealed motor unit that cannot be taken apart and fixed at home, so when it stops working, leaks, or jams beyond clearing, replacement is the standard solution.
The job takes two to four hours for a first-timer and requires basic hand tools you likely already own: an adjustable wrench, a screwdriver, and a bucket. You will turn off power at the breaker, disconnect the plumbing, unbolt the old unit, and install the new one in reverse order. No special skills or permits are needed for a homeowner doing their own work.
Key Takeaways
- Turn off power at the circuit breaker before touching any part of the disposal, and test the switch to confirm power is off.
- Disconnect the drain pipe and the electrical connection under the sink, then unbolt the mounting ring to remove the old unit.
- Install the new disposal by reversing the steps: mount it, reconnect the drain, and wire it to the outlet or hardwire it to the breaker.
- Test with the sink empty and the stopper in place, then run water for 30 seconds to check for leaks before using normally.
- If your old disposal was hardwired (no plug), hire an electrician to wire the new one unless you have experience with electrical work.
Gather Your Tools and Materials Before You Start
You will need an adjustable wrench, a flathead screwdriver, a Phillips screwdriver, a bucket or large bowl, a flashlight, and a towel. Have the new disposal unit on hand—measure your old one or check your sink cabinet to confirm it will fit. Most standard disposals are the same size, but compact models exist for tight spaces.
If your old disposal is plugged into an outlet under the sink, you are in luck: you can straightforward unplug the new one and plug it in. If it is hardwired (connected directly to the electrical panel with wires), you will need an electrician to wire the new unit. Do not attempt hardwiring yourself unless you are trained in electrical work.
Place the bucket under the drain connection before you start—there will be standing water in the pipes. Have a towel ready to catch drips and wipe your hands.
Turn Off Power and Disconnect the Plumbing
Go to your circuit breaker and switch off the breaker labeled for the kitchen disposal or kitchen outlets. Return to the sink and flip the disposal switch—nothing should happen. If it does, you turned off the wrong breaker; go back and find the right one.
Reach under the sink and locate the drain pipe connected to the disposal. This is usually a large plastic or metal pipe that angles downward. Place your bucket underneath and loosen the connection with your wrench. The pipe will come free and water will drain into the bucket. If there is a second pipe (the overflow), disconnect that too.
If your disposal is plugged in, unplug it now. If it is hardwired, you will see a wire connection box where the power enters the unit. Do not touch the wires yet—wait until you have removed the disposal from the sink.
Remove the Old Disposal from the Mounting Ring
Look up into the sink opening from below. You will see the disposal hanging from a metal ring bolted to the underside of the sink. This is the mounting ring. Locate the three bolts that hold the disposal to this ring—they are usually arranged in a triangle around the unit.
Using your wrench, loosen each bolt by turning counterclockwise. Do not remove them completely yet; loosen them until the disposal hangs loose but is still supported by the bolts. Once all three are loose, carefully lower the disposal and remove the bolts by hand. The unit will now be free to slide out.
If the disposal is hardwired, you can now safely disconnect the wires. There will be a wire connection box held in place by a single screw. Unscrew it, and the wires will come free. Set the old disposal aside.
Install the New Disposal and Reconnect the Drain
Before you install the new unit, check the mounting ring. If it is still attached to the sink, you can reuse it. If it came off with the old disposal, you will need to install a new mounting ring—this usually comes with the new disposal and takes 10 minutes with a screwdriver.
Slide the new disposal up into the sink opening and align it with the mounting ring. Insert the three bolts through the disposal and into the ring, then tighten them evenly by hand. Do not use the wrench yet; hand-tighten first to make sure everything is aligned. Once hand-tight, use your wrench to tighten each bolt a quarter turn at a time, rotating around the triangle so the pressure is even. Stop when the disposal is snug—do not over-tighten.
Reconnect the drain pipe by sliding it back onto the outlet and tightening the connection with your wrench. If there was an overflow pipe, reconnect that too. Turn on the water and let it run into the sink for 10 seconds while watching underneath for leaks. If you see water dripping, tighten the connection a little more.
Reconnect Power and Test the Unit
If your disposal is a plug-in model, straightforward plug it into the outlet under the sink. If it is hardwired, you will see the wire connection box on the new unit. Match the wires: black to black, white to white, and bare copper to bare copper. Twist each pair together, then screw the connection box closed. Once the wires are connected, go to the breaker and switch it back on.
Return to the sink and place the stopper in the drain opening. Turn on the cold water and let it run for 30 seconds. Do not turn on the disposal yet—just let water fill the sink. Watch underneath for leaks. Once you are sure there are no leaks, turn off the water.
Now flip the disposal switch. It should run smoothly with a steady hum. Let it run for 10 seconds, then turn it off. Turn the water back on and run the disposal for another 10 seconds while water flows. This clears any debris from installation. Turn everything off and you are done.
Common Mistakes to Avoid
The biggest mistake is forgetting to turn off power at the breaker. Even with the switch off, the unit is live and can start unexpectedly. Always kill the breaker first and test the switch to confirm.
The second mistake is over-tightening the mounting bolts. This can crack the sink or strip the bolts. Hand-tighten first, then use the wrench for a quarter turn on each bolt. If the disposal is snug and does not move, stop.
The third mistake is not placing a bucket under the drain before disconnecting it. You will have a sink full of standing water that will spill everywhere. Place the bucket first, every time.
Finally, do not attempt to hardwire a new disposal if you have never done electrical work. A loose wire connection can cause a fire or electrocution. Hire an electrician for this step—it costs $100 to $200 and takes 30 minutes.
Frequently Asked Questions
Can I install a new disposal if my old one is still plugged in?
Yes, but only if you unplug it first. Never work on a plugged-in disposal, even if the switch is off. Unplug it, then proceed with removal. If it is hardwired, turn off the breaker and test the switch before touching anything.
What if water keeps dripping from the drain connection after I tighten it?
The rubber gasket inside the connection may be worn or misaligned. Loosen the connection, slide the pipe off, and check the rubber ring. If it looks cracked or flattened, replace it—they cost a few dollars at any hardware store. Slide the new gasket on and reconnect.
Do I need a plumber to install a new disposal?
No, if your old disposal was plug-in and your new one is also plug-in. The plumbing connections are straightforward hand-tightened fittings. If your old disposal was hardwired, hire an electrician to wire the new one. The plumbing part you can do yourself.
How long does a new disposal usually last?
Most disposals last 8 to 15 years depending on use and water hardness. If you grind hard items like bones or ice regularly, it will wear out faster. Proper use—grinding soft food waste with plenty of water—extends the life.
What should I do if the new disposal leaks from the bottom?
A leak from the bottom of the unit itself means the seal inside has failed. This cannot be repaired—the disposal must be replaced. A leak from the drain connection means the gasket is loose or damaged, which you can fix by tightening or replacing the gasket as described above.